1. Field of the Invention
The present invention relates to an image display apparatus and an image data writing method and, more particularly, to an image display apparatus which detachably holds a thin display device and which can function as a printer or a display and an image data writing method therefor.
The invention relates to a thin display file and a data communication method for a thin display file and, more particularly, to a thin display file using a plurality of stacked thin display devices and a data communication method for the thin display file.
In addition, the invention relates to an image display apparatus and an image display system and, more particularly, to an image display apparatus which can realize a large screen by combining a plurality of image display apparatuses (causing a plurality of image display apparatuses to abut) and an image display system for realizing a large screen by combining a plurality of image display apparatuses.
2. Description of the Related Art
In recent years, with the development of information-oriented society, as a thin display device, so-called electronic paper that has both the advantages of electronic display and paper attracts attention. A large number of techniques related to the electronic paper are proposed (see, for example, Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 9-101864, Patent Document 2: JP-A No. 2001-312427, Patent Document 3: JP-A No. 6-274129, and Patent Document 4: JP-A No. 11-202804).
For example, in the technique of Patent Document 1 (in particular, page 7, FIG. 1), tablet type electronic paper is proposed. In the electric paper described in Patent Document 1, a digitizer board is connected to a commercial outlet, a memory chip is mounted on a digitizer board, and digital paper is loaded as electronic paper. In this state, when letters or the like are input to the surface of an input film with handwriting, the various pieces of information input with handwriting are recognized as characters by the digitizer board, so that the pieces of information are displayed as the characters on the digital paper by heating of a heat panel of the digitizer board. In this manner, since the digital paper on which the various pieces of information are displayed maintains the display images even when unloaded from the digitizer board, the digital paper can be handled like paper. On the other hand, when the digital paper on which the various pieces of information are displayed is loaded on the digitizer board, the displayed information can be erased or corrected.
It is considered that a thin display device is used such that a plurality of thin display devices are staked on each other. Therefore, for example, Patent Document 2 (in particular, page 1, FIG. 1) proposes the following. That is, connection terminals having physical or electrical connection functions are arranged on sheets of electronic paper and main bodies, and the thin display devices are bundled in a file form. In Patent Document 1, the electronic paper can be detachably loaded on the main body, display data is recorded in a nonvolatile memory arranged in a display unit of the electronic paper, so that the electronic paper unloaded from the main body holds the display contents. In Patent Document 2, the contents of a page can be held such that the page is opened.
In this manner, thin displays can be handled as a file like sheets of paper, and the reading properties of sheets of paper can be achieved.
In addition, as described in the technique described in Patent Document 3 (in particular, pages 6 to 7, FIG. 6), it is proposed that electronic paper can be used as a display device for a personal computer.
However, in the technique described in Patent Document 1, since tablet type electronic paper is used, the tablet type electronic paper disadvantageously occupies a large plane area.
In the technique described in Patent Document 2, when it is considered that electronic paper is used together with a display device such as a liquid crystal screen of a personal computer, information written in the electronic paper cannot be easily read.
Furthermore, as in Patent Document 2, when a plurality of thin display devices are connected to host apparatuses (in Patent Document 2, main bodies), conventionally, in order to identify the plurality of thin display devices, the host apparatuses must be connected to the thin display devices in one-to-one correspondence. Since connection connectors are arranged on the thin display devices, when a large number of thin display devices are stacked on each other, the positional relationships, e.g., vertical positions, of the plurality of thin display devices are cumbersomely identified.
In addition, the number of connection positions is increased by stacking a plurality of thin display devices on each other, so that the costs disadvantageously increase.
Further more, in the technique described in Patent Document 3, in consideration of use of sheets of electronic paper, writing in the sheets of electronic paper is not achieved. Since the display devices are arranged as main display devices, when it is considered that electronic paper is handled as a print printed by a printer, the display devices are low in usability.
In general, page sizes of documents expressed by document files formed as electronic files which can be handled on a computer are various sizes such as A-3 and A-4 sizes.
In contrast to this, in A-4 size display electronic paper which cannot be updated on real time, a document having a page size of A-3 size cannot be displayed without changing the page size. In A-4 size display electronic paper which can be updated on real time, when a document having a page size of A-3 size is directly displayed, a display images must be scrolled. The essential function of the electronic paper is spoiled, and the electronic paper is not different from a conventional electronic display.
Therefore, in order to realize display of documents having page sizes of A-4 size and A-3 size which are popularly handled as general documents by the same electronic paper without any problem, electronic paper for A-3 size must be prepared.
However, display schemes of electric paper include great variety of schemes. In general, as an image display size (screen size) increases, a yield in manufacture tends to decrease. In particular, in electronic-device-like electronic paper such as electronic paper using a liquid crystal, like a general liquid crystal display, this tendency is conspicuous. Therefore, preparation of A-3 size electronic paper unnecessarily increases the costs for a user who wants to perform only display of an image having a page size of A-4 size.
On the other hand, as applications which can give the priority of electronic paper full play, applications having various screen sizes ranging from a small screen size of 10 cm or less for a mobile terminal device or the like to a large screen size, which is larger than A-3 size, for displaying newspaper, a signboard, or advertisement are considered. In this case, the yield of the electronic paper having a screen size which is larger than A-3 size is smaller than that of an electronic paper having a screen size which is equal to or smaller than A-3 size, and the costs jump.
In general, since electronic paper cannot be folded, electronic paper having a large screen size is inconveniently carried. With respect to this point, electronic paper having a large screen size has a disadvantage.
In order to solve the problems in cost and portability of electronic paper having a large screen size, the following is considered. That is, sheets of electronic paper are adjacently arranged on a plane, so that an image which is larger than the screen size of each sheet of electronic paper is displayed by combining the display surfaces of the sheets of electronic paper. As described above, as a technique related to display of an image having a large size and obtained by combining a plurality of display devices, there is a technique in which a plurality of cathode ray tubes and control devices are connected to each other in one-to-one correspondence to cause the control devices to control display of the images on the cathode ray tubes (for example, Patent Document 5: see Japanese Patent Application Publication (JP-B) No. 50-32009).
However, in this technique, the plurality of cathode ray tubes and the control devices must be connected to each other in one-to-one correspondence. Therefore, as a result, the costs disadvantageously increase.
More specifically, in this technique, the number of connections between the display devices and the control devices increases as the number of display devices is increased to enlarge the display area. Therefore, since the display devices and the control devices are connected to each other with relatively expensive wire harnesses, the increase in number of connections between the display devices and the control devices increases the number of wire harnesses. As a result, the costs of the apparatus as a whole increase.
As a technique which realizes a large screen such that sheets of electronic paper applied as display devices are adjacently arranged on a plane, the following technique may be considered. That is, images to be displayed on the sheets of electronic paper are displayed in advance, respectively, and the sheets of electronic paper are adjacently and planarly arranged by manpower in such a state that the display states of the sheets of electronic paper are held. However, in this technique, the sheets of electronic paper must be arranged at appropriate positions by manpower each time a display image is updated. This operation is very cumbersome.
The invention has been made to solve the above problems, and has as one object to provide an image display apparatus which holds a thin display device and which can be used in many different ways and an image data writing method therefor.
It is another object of the invention to provide an image data writing method for a convenient thin display device when a plurality of thin display devices are held.
It is still another object of the invention to provide a thin display file which can perform display control with a simple structure and simple communication and a data communication method for the thin display file.
It is still another object of the invention to provide an image display apparatus and an image display system which can display a large-size image without increasing costs.